Arks

Ponderous arks are the largest of the three Chesapeake Bay ark species. They are perfectly heart-shaped when viewed from the side. (Bill Frank/Jax Shells)

Arks are boxy bivalves with thick, white, ribbed shells. They live in the salty waters of the lower Chesapeake Bay.

Three species of arks can be found in the Chesapeake Bay:

Ponderous ark, Noetia ponderosa

Blood ark, Anadara ovalis

Transverse ark, Anadara transversa

Appearance:

Arks have thick, white, boxy shells with many ribs. Ponderous arks are heart-shaped when viewed from the side. Blood arks and ponderous arks are often covered with a thick, dark brown, felt-like "periostracum," or outer-most layer. The ponderous ark is the largest of the three species, growing to 2.5 inches in length. The transverse ark is the smallest, growing to about 1 inch in length.

Habitat:

Usually burrow into bottom sediments, using their large foot to firmly achor themselves. Blood arks live in shallow waters, while ponderous arks live in both shallow and deep waters. Transverse arks often do not burrow, but rather live among bay grass stems.

Range:

Found in the salty waters of the lower Chesapeake Bay.

Feeding:

Arks eat plankton and detritus, feeding through a figure eight-shaped opening in the mantle.

Reproduction and Life Cycle:

Spawning occurs throughout most of the year, with peaks in summer and autumn. Gametes mature in the spring.

Other Facts:

Arks’ thick, heavy shells are able to withstand strong waves and currents.

Ark shells are often found washed up on lower Bay beaches.

The blood ark gets its name from its red blood; most other bivalves have clear blood.